J-Bar
Member
Perhaps you guys can enlighten me on what causes key holing to happen?
If the gun was used, clean the chambers and barrel thoroughly.
Look at the muzzle's crown. Any damage to the crown can upset the bullet's flight.
Did you try a few rounds of Velocitor?
Not trying to put you on the spot here, just trying to narrow down the possibilities:
Without photos of the target I hesitate to ask, but are you sure it was keyholing? I sometimes get tears around the bullet hole that could be mistaken for keyholes but is actually caused by a thin paper target dangling freely without any backing support. Were the "keyhole" groups nice and small or did the groups look like a shotgun pattern? Did you shoot over a rest?
I'm not familiar with the Pathfinder. Pictures on Gunbroker show an external hammer. Did you try shooting it in single action? How were the SA groups?